Doppler tomography of Cataclysmic Variables

The study of cataclysmic variables (CVs), and in particular of the evolution of their accretion discs throughout their different brightness states, has benefited largely from the use of indirect imaging techniques. I report on the latest results obtained from Doppler tomography of CVs concentrating mainly on results published since the 2000 Astrotomography meeting in Brussels. Emphasis is given to the spiral structures found in the accretion discs of some CVs, to the evolution of these structures throughout quiescence and outburst, and to our search for them in more systems.Comment: 4 pages, 1 figure. Accepted for publication in AN. Proceedings of the Astrotomography Joint Discussion 09 of the IAU General Assembly 2003. Uses an.cl

Local area network with fault-checking, priorities, and redundant backup

This invention is a redundant error detecting and correcting local area networked computer system having a plurality of nodes each including a network connector board within the node for connecting to an interfacing transceiver operably attached to a network cable. There is a first network cable disposed along a path to interconnect the nodes. The first network cable includes a plurality of first interfacing transceivers attached thereto. A second network cable is disposed in parallel with the first cable and, in like manner, includes a plurality of second interfacing transceivers attached thereto. There are a plurality of three position switches each having a signal input, three outputs for individual selective connection to the input, and a control input for receiving signals designating which of the outputs is to be connected to the signal input. Each of the switches includes means for designating a response address for responding to addressed signals appearing at the control input and each of the switches further has its signal input connected to a respective one of the input/output lines from the nodes. Also, one of the three outputs is connected to a repective one of the plurality of first interfacing transceivers. There is master switch control means having an output connected to the control inputs of the plurality of three position switches and an input for receiving directive signals for outputting addressed switch position signals to the three position switches as well as monitor and control computer means having a pair of network connector boards therein connected to respective ones of one of the first interfacing transceivers and one of the second interfacing transceivers and an output connected to the input of the master switch means for monitoring the status of the networked computer system by sending messages to the nodes and receiving and verifying messages therefrom and for sending control signals to the master switch to cause the master switch to cause respective ones of the nodes to use a desired one of the first and second cables for transmitting and receiving messages and for disconnecting desired ones of the nodes from both cables

Accurate control of a Bose-Einstein condensate by managing the atomic interaction

We exploit the variation of the atomic interaction in order to move ultra-cold atoms across an AC-driven periodic lattice. By breaking relevant symmetries, a gathering of atoms is achieved. Accurate control of the gathered atoms positions can be demonstrated via the control of the atomic localization process. The localization process is analyzed with the help of the nonlinear Floquet states where the Landau-Zener tunneling between states is observed and controlled. Transport effects in the presence of disorder are discussed.Comment: 14 pages, 5 Figures, PACS numbers: 03.75.Lm, 05.60.-k, 63.20.P

Spectral atlas of dwarf novae in outburst

Up to now, only a very small number of dwarf novae have been studied during their outburst state (~30 per cent in the Northern hemisphere). In this paper we present the first comprehensive atlas of outburst spectra of dwarf novae. We study possible correlations between the emission and absorption lines seen in the spectra and some fundamental parameters of the binaries. We find that out of the 48 spectra presented, 12 systems apart from IP Peg show strong HeII in emission: SS Aur, HL CMa, TU Crt, EM Cyg, SS Cyg, EX Dra, U Gem, HX Peg, GK Per, KT Per, V893 Sco, IY UMa, and 7 others less prominently: FO And, V542 Cyg, BI Ori, TY Psc, VZ Pyx, ER UMa, and SS UMi. We conclude that these systems are good targets for finding spiral structure in their accretion discs during outburst if models of Smak (2001) and Ogilvie (2001) are correct. This is confirmed by the fact that hints of spiral asymmetries have already been found in the discs of SS Cyg, EX Dra and U Gem.Comment: 16 pages, 14 figures. To be published in MNRA